I have friends with all three that you list and I have used each. S1's quality is not as good in output, build and usability (flash sucks). T33 and T5 were very similar, the door on the T5 seemed to be problematic on friends...

But as many others will probably tell you, take a look at the Canon SD450. I am NOT a Canon fan, and I do like Sony and Nikon Cameras (I own a DSC-W1 and D70) but if I was looking for a pocket camera today I would go for the SD450.